Yes, and for a good reason! Cel-Fi is controlled by and operates as an extension of an operator’s network. This is what allows Cel-Fi (by regulatory authority) to boost signals about 1000x more than other solutions, and therefore cover very large areas even if the original network signal is weak. And it works very well.
Broad-spectrum repeaters can cause interference and damage to networks, so operators have adopted a strict policy against the use of these legacy signal boosters on their own networks. However, Cel-Fi (the only smart signal booster of its kind), is authorized for use by each carrier and allowed to transmit on their licensed spectrum without ruining things for anyone else.